A hand written signature is often used for the identification of individuals. In most cases, the freshly written signature is used visually for the identification of an individual by comparison with a signature signed elsewhere, e.g. on a credit card, signature card or some other identification paper at a previous time. A forged signature, if done adeptly, may be indistinguishable from a genuine signature by visual comparison. Therefore visual comparison offers a very ineffective deterrent against forgeries.
The use of a writing utensil with a pressure recorder for monitoring the signing of the signature is known in the prior art. This method permits the detection of writing pressure which occurs between the writing utensil and the writing surface as a function of time. The detected pressure may be converted to an electrical signal which is characteristic for a signature and which may be recorded with a recording device. For the identification of an individual this process is repeated and the pressure distibution function so obtained is compared with the formerly recorded pressure distribution function. As a result forgeries are made considerably more difficult because the pressure distribution curve cannot be as easily imitated as the visual aspect of the writing.
It is known in the art to translate handwriting into electrical signals by detecting the position of the writing instrument in two dimensions and producing two electric signals which represent the coordinates of the instantaneous point of contact of the writing instrument on the writing plane. From the two electric signals the vectorial speed and acceleration of the writing stylus are deduced by differentiation and the latter are then converted into digital signals. The speed and the acceleration of the signature represent identification marks which are difficult to imitate. However the cost of the apparatus for employing this technique is very great.
Accordingly, it is a primary object of the present invention to provide an inexpensive means for identifying handwriting.
Another object of the present invention is to provide an apparatus and method for producing an electrical signal in response to writing speed as well as writing pressure.
Still another object of the present invention is to provide an inexpensive means for converting pressure variations between a writing instrument and a writing surface into an electrical signal corresponding to identifying characteristics of the handwriting.
These and other objects and features of the invention will become apparent from the claims and from the following description when read in conjunction with the appended drawings.